Thingvellir National Park, Iceland - Tourists walk through Iceland's Thingvellir rift valley, the only place on Earth where the continental boundary of the Mid-Atlantic Ridge rises above sea level. This image is from Birth of Europe.

SCREEN GRAB: Nearly 40 feet long and weighing up to 20 tons, the mysterious whale shark is the largest fish in the sea. Ironically, its survival depends on some of the tiniest creatures. This image is from Great Migrations.